Abstract
Flame propagation is measured in a 4-valves per cylinder spark-ignition engine using optical fibers. The engine speed is increased from 2000rpm to 4000rpm with 500rpm interval at WOT. Flame propagation data are acquired at every 0.1 degree of crank angle for 80 cycles with cylinder pressure. The results show that flame propagates faster to the exhaust valve side than to the intake valve side. An engine simulation program is developed to compare the calculated flame propagation with the experimental results. The combustion model in the program uses a refined combustion model based on the Blizard and Keck's entrainment and burn-up model. The new model is refined by including the effects of flame stretch, turbulent length scale band-pass filter and a variable that considers the flame size and the flame contacting area of the chamber wall and piston. The predicted results show reasonable agreement with the measured flame propagation using optical fiber technique except in the early flame growth stage.